Field guide
CSV Cleanup Checklist Before Importing Data
A practical CSV cleanup checklist for headers, delimiters, encodings, duplicate rows, dates, IDs, and final import verification.
Read guidePractical answers, followed by the tools to do the work.
Follow step-by-step guides for files, calendars, web security, identifiers, images, and date calculations, then open the relevant MiniUtil tools without restarting your workflow.
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Field guide
Security Headers: A Safe Deployment Order
Roll out CORS, CSP, Permissions-Policy, caching, SRI, and security.txt in an order that limits breakage and contradictory settings.
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UUID v4 vs UUID v7 vs ULID
Compare UUID v4, UUID v7, and ULID for randomness, sort order, database indexes, timestamp visibility, and ecosystem compatibility.
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RRULE vs Cron: Which Schedule Format Fits?
Choose between iCalendar RRULE and cron by comparing calendar events, server jobs, time zones, exceptions, dialects, and daylight saving behavior.
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How to Create an ICS Calendar File
Create an ICS calendar file for Google Calendar, Outlook, or Apple Calendar with correct dates, time zones, recurrence, and validation.
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How to Convert CSV to JSON Without Losing Data
Convert CSV to JSON while preserving quoted fields, leading zeroes, dates, empty values, encodings, and a predictable object structure.
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How to Decode a JWT and Read Its Claims Safely
Decode a JWT locally, understand header and payload claims, check timestamps, and distinguish readable token data from a verified signature.
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WebP vs PNG vs JPG: Which Image Format Should You Use?
Compare WebP, PNG, and JPG for photos, transparency, sharp graphics, file size, quality, compatibility, and practical web delivery.
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How to Calculate Business Days Between Two Dates
Calculate business days accurately by defining inclusive dates, weekends, holidays, regional calendars, and time-zone boundaries first.
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How to Create a Content Security Policy Without Breaking Your Site
Build a Content Security Policy by inventorying resources, choosing directives, testing report-only mode, and tightening enforcement safely.
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How to Combine Photos and Graphics Into One PDF
Convert HEIC photos and vector graphics to a shared format, combine them into a single PDF in the right order, and extract pages back out when needed.
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Content-Disposition Filenames With Spaces and Non-ASCII Characters
Set a download filename that survives spaces, accents, and non-Latin scripts using the Content-Disposition filename and filename* parameters.
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Why a Subresource Integrity Hash Fails
Diagnose Subresource Integrity failures: changed CDN bytes, a missing crossorigin attribute, algorithm selection, and hashing the wrong build.
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How to Share a HAR File Without Leaking Credentials
A HAR capture contains cookies, authorization headers, tokens, and request bodies. Redact them before sending the file to support or a vendor.
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Unix Timestamps: Seconds, Milliseconds, and 2038
Tell seconds from milliseconds at a glance, avoid factor-of-1000 conversion bugs, and understand what the 2038 limit does and does not affect.
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ISO Week Numbers: Why Week 1 Is Not Always in January
How ISO 8601 defines week 1, why some years have 53 weeks, and why the week-numbering year can differ from the calendar year of the same date.
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OAuth PKCE: code_verifier, code_challenge, and S256
How PKCE protects an authorization code exchange, what the verifier and challenge must contain, and why S256 should always be used instead of plain.
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